Field of the Invention
The present invention relates to a dispensing device for dispensing compressed fluid from a pressurized container.
Introduction
Dispensing fluid, particularly foamable fluid, from a compressed can is useful for many products including whipped dairy toppings and spray foam for sealing and thermal insulation applications. Foamable fluid is often available as foamable liquid under pressure in a can that is dispensed through an application tube attached to a valve or valve stem on the can. Upon release from the pressurized can the foamable fluid expands into foam.
One challenge with spray foam is that residual foamable formulation in the application tube of the dispenser is free to continue to expand after applying spray foam formulation to a location. The residual foamable liquid continues to expand and expel from the application tube even after application of the foamable liquid is complete. The expanding residual foamable liquid can drip from the application tube to create unintended messes. Alternatively, the user must periodically wipe clean the dispensing end of the application tube as residual foamable liquid expands within the application tube. To avoid drips and the need to continually wipe the end of an application tube, it is desirable to have a dispensing device for use with compressed expandable liquids that would obviate continuous expansion of residual foamable liquid out from an application tube after desired application of the foamable liquid is complete. Moreover, it is desirable to have such a dispensing device that is operable with a single action and using a single hand to dispense the foamable fluid and then to seal the application tube when done dispensing.
U.S. Pat. No. 5,549,226 ('226) discloses a device for operating propellant cans that can be useful for addressing the aforementioned problem. The device in '226 comprises a bendable application tube that can bend back on itself and the open end of the tube placed over a nipple to seal it. Inserting a nipple into the end of an application tube from outside the application tube will itself displace fluid out from the application tube around the nipple resulting in foam being undesirably disposed around the nipple area and possibly the fingers of a user. In contrast to the device of '226, it is desirable to avoid having to insert anything from outside the dispensing tube into the end of the dispensing tube in order to seal the end. It also requires two hands to reposition the nipple into the straw, during which time foam can undesirably continue to expel from the straw.
The Dow Chemical Company offers a foam dispensing gun for GREAT STUFF PRO™ brand spray foam. The spray gun is available in three different grades: PRO 13, PRO 14 and PRO 15. Each of the guns has a port onto which a can of GREAT STUFF PRO™ brand spray foam attaches thereby releasing the compressed foam formulation into a barrel of the gun.
Upon attaching the can to the dispensing gun, the valve of the can is held in the open position so pressurized contents of the can are continuously free to exit the can through the valve. Therefore, the dispensing gun controls when the pressurized contents can flow through the dispensing gun and when they cannot. Extending through the barrel is a rod that is spring loaded to seal from inside the barrel an outlet or dispensing end of the barrel. A trigger is attached to the spring loaded rod so that upon pulling the trigger the rod is retracted from the dispensing end of the barrel and foam formulation is free to flow from the can through the barrel around the retracted rod and out from the dispensing end. Upon release of the trigger the spring repositions the rod back into sealing position in the dispensing end of the barrel. This dispensing gun design requires a rod to extend through the barrel thereby decreasing the open volume inside the barrel available for transporting foam formulation and thereby restricting foam formulation flow through the barrel. It is desirable to have a dispensing device capable of sealing but without requiring a rod to extend through the entire barrel of the dispensing device. Moreover, it is desirable to have a dispensing device that does not hold the pressurized container in the open position at all times, but rather only opens the valve stem of a pressurized container when dispensing of the contents of the container is desired.
U.S. Pat. No. 8,720,747 discloses a single-action dispenser that requires a plug in the dispensing straw that is pressed into the exit opening of the straw by fluid pressure to seal the straw and is displaced from the exit opening into the straw to dispense the foamable fluid from the straw. It is desirable to identify a dispenser that does not require fluid pressure to seal the dispenser. It is further desirable to avoid having to displace a plug into the straw to dispense the fluid because the plug can still inhibit fluid flow in the straw.